Messages in this thread Patch in this message | | | Date | Tue, 2 Apr 2024 18:52:12 +0530 | Subject | Re: [PATCH] drm/panthor: Fix NULL vs IS_ERR() bug in panthor_ioctl_tiler_heap_destroy() | From | Harshit Mogalapalli <> |
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Hello Boris,
On 02/04/24 18:03, Boris Brezillon wrote: > Hello Harshit, > > On Tue, 2 Apr 2024 03:33:58 -0700 > Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> wrote: > >> panthor_vm_get_heap_pool() returns ERR_PTR on failure. >> >> Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block") >> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> >> --- >> This is spotted by smatch and the patch is only compile tested >> --- >> drivers/gpu/drm/panthor/panthor_drv.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c >> index 11b3ccd58f85..050b905b0453 100644 >> --- a/drivers/gpu/drm/panthor/panthor_drv.c >> +++ b/drivers/gpu/drm/panthor/panthor_drv.c >> @@ -1090,8 +1090,8 @@ static int panthor_ioctl_tiler_heap_destroy(struct drm_device *ddev, void *data, >> return -EINVAL; >> >> pool = panthor_vm_get_heap_pool(vm, false); >> - if (!pool) { >> - ret = -EINVAL; >> + if (IS_ERR(pool)) { >> + ret = PTR_ERR(pool); > > Actually, panthor_vm_get_heap_pool() will return NULL if there's no > heap pool attached to this VM and create=false, so this was correct. > This being said, I'm fine making that consistent by returning > ERR_PTR(-ENOENT) instead of NULL in that case. This way we don't have > two different semantics based on the 'create' value. >
Thanks for explaining. I missed the case where create is false and there is no heap pool attached, so panthor_vm_get_heap_pool() can return NULL.
1878 * 1879 * Return: A valid pointer on success, an ERR_PTR() otherwise. 1880 */ 1881 struct panthor_heap_pool *panthor_vm_get_heap_pool(struct panthor_vm *vm, bool create)
The documentation says it returns ERR_PTR() on failure, so is it worth doing something like:
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c index fdd35249169f..e1285cdb09ff 100644 --- a/drivers/gpu/drm/panthor/panthor_mmu.c +++ b/drivers/gpu/drm/panthor/panthor_mmu.c @@ -1893,6 +1893,8 @@ struct panthor_heap_pool *panthor_vm_get_heap_pool(struct panthor_vm *vm, bool c vm->heaps.pool = panthor_heap_pool_get(pool); } else { pool = panthor_heap_pool_get(vm->heaps.pool); + if (!pool) + pool = ERR_PTR(-ENOENT); } mutex_unlock(&vm->heaps.lock);
and change all callers of panthor_vm_get_heap_pool() to only check for IS_ERR() ?
> Oh, and please merge everything into a single patch instead of one patch > per call-site. >
Sure, I noticed one after the other. I will fix them together in v2.
Thanks, Harshit > Regards, > > Boris > >> goto out_put_vm; >> } >> >
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